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The Woodburning Book

 

Edited extracts from the 1977 book pictured below, by kind permission of David Thear of Broad Leys Publishing

The Woodburning Book cover

 

 

 

Wood As Fuel

Inflation, particularly the rise in the prices of fuels, has caused all of us to look carefully at our costs and what we are buying. Is there some way in which it is possible to heat our homes in winter, or heat our water at a lower cost? Perhaps there is. Using wood as an alternative or supplementary fuel may save a great deal.

Wood has half the calorific value of coal, and at the current bulk purchase price in country areas of 50/ton, is well worth considering as fuel. However, to make it worthwhile, it is necessary to use it wisely and to extract the maximum heat from it. There are two essential ways to achieve this, by burning only seasoned wood and by utilising an efficient woodstove.

In Britain we have traditionally burnt togs in the home in an open fireplace. This is extremely attractive but very wasteful, as 80% of the heat disappears up the chimney. Furthermore, the higher you stoke the fire, the more oxygen it demands, and the greater those spine chilling draughts. Indeed, in a centrally heated house, an open fireplace can draw valuable heat up the chimney and away.

 

Slow Combustion Woodstove

The most efficient type of woodstove is basically a metal box which stands clear of the wall and is connected to the chimney by a short flue pipe. This box, if constructed well, with primary and secondary air inlets, burns wood completely to fine ash. It can be regulated to do so slowly and to give off an even temperature for the whole burning cycle of the wood. Thus, instead of obtaining heat from only two logs out of ten put on the open fire, in a good woodstove we can obtain the heat from at least five, and maybe as many as eight out of ten.

When wood burns, first the absorbed water is driven off. After about 300F Our wood begins to break down chemically, giving off volatiles such as carbon monoxide and sulphur. To burn these, extra oxygen is needed and this is provided by a secondary air inlet.

A good Scandinavian woodstove like the Jotul 118 burns logs from end to end like a cigar, and forces the air inside the stove into an S-shaped pattern, thus ensuring complete combustion. It achieves this at a near constant temperature throughout the burning cycle. Some Scandinavian woodstoves are constructed of cast iron, instead of the sheet steel used elsewhere. The Scandinavians have a long experience in this field, and claim that iron retains heat longer and distributes it more evenly than steel. Further, that it will last better.

A poorly made woodstove, which is not precision built to be completely airtight, will not achieve the very slow combustion necessary to extract the maximum heat and return it to the room. It will produce the required heat at the expense of using far more wood and, if not robustly constructed, will deteriorate rapidly in is few years.

The efficiency of a woodburning stove is rated by the amount of heat from the combustion that is returned to the room. Similarly with a boiler, how much heat is transferred to the water.

Jotul 118 air movement

S-shaped pattern of air movement ensures complete combustion in the Jotul 118

It is not possible to make precise statements about different stoves because their performance depends on too many factors. For example, the type of wood, how much moisture it includes, how closely it is packed in the burner, the type of chimney, how dry it is and whether gales are causing downdraughts, and so on. However, anyone considering purchasing a woodstove can try to assess its capability and whether it is good value for money by checking the following points:

 

1.         How long has the manufacturer been producing woodstoves? What is their reputation?

2.         Is it built to last? What metal is it? How thick is the metal? How are the joints sealed and are the doors ground to fit precisely so that the stove is completely airtight?

3.         How long are the logs it will accept? This can save much sawing in a year. How often does it need reloading and how long can it keep in on a full load when turned down? What is its claimed output?

4.         Obtain the names of other customers in your area and ask them for their findings. Does the stove give out as much heat as claimed? Check the kind of fuel used and whether it is seasoned.

5.         Does the performance vary at different times? If you can, check with more than one customer, as it would be a shame to judge a woodstove adversely if one person has a problem chimney.

 

Dry Wood

The wood you use in your stove should be thoroughly seasoned. Fresh cut timber is called green and can be more than 50% water. Drying out the wood by storing can reduce this to about 20%. The best time to cut wood is in the Summer when much of the sap is drawn out in the leaves. Cut and stack it in dry and airy conditions for at least 6 months before burning, and preferably a year.

The drier the wood you burn and the more efficient the combustion in your woodstove, the less tar deposits you will get in your chimney. However, you will still get some, and the chimney should be swept twice a year. 

With a box stove fitted into a closed fireplace by a short flue pipe, it is a good idea to cut a soot cleaning hole with a well fitted door above the fireplace, for the sweep to gain access with a vacuum cleaner. You can hang a picture over this door when it is not being used. 

 

Sources of Wood 

 1.         There is much dead wood already available in the countryside, often just left to rot. Many stretches of woodland, particularly private woodland, are full of trees carrying dead wood and in need of pruning. Often the dead branches have already fallen and are littering the forest floor. In fact many stretches of private woodland are downright dangerous places to be in. 

 2.         On common land it is permissible to collect fallen, dead wood. 

 3.         Many farms have old gates, fencing and posts, and timber from demolished barns. 

 4.         Many trees are felled annually for road and building development. Ask the 

foreman what the fate of the trees is likely to be. 

 5.         In towns, demolition sites always produce timber which is often burnt on site.  

6.         Local Authority Parks Departments too are pruning and taking out trees. These are usually burnt at some central point and are worthy of investigation. 

7.         Sawmills often sell off-cuts which make excellent fuel, particularly as no sawing is required.  

8          Tree surgeons, loppers and contract gardeners are worth approaching; their addresses will be in the Yellow Pages Guide. 

   

It is in the search for wood that a car trailer comes into its own. Here, some sort of bartering arrangement between friends, can be beneficial. The authors of this book do not have a trailer, but have the use of one in exchange for the loan of their grain grinder, used for the preparation of poultry food. 

   

Newspaper Logs 

Newspaper is, after all, processed wood, and there's an awful lot of newspaper lying around. 

Old newspapers and magazines can quite easily be converted into 'logs' by rolling up as tightly as possible and securing with some bits of old wire. If these are tossed into a container with a few inches of waste oil and left for a few days, the absorbed oil will ensure a thorough burning. Leave to 'dry' before putting them in the burner where they will last for a couple of hours.  

The secret is in rolling them really tightly, and if you don't have the muscle power, there is a piece of equipment called the Logrol which will do this for you. 

 

Buying Wood 

You can of course buy wood in bulk either by volume or by the ton. Volume is measured in cubic feet. If you are offered wood by other terms, conversion is as follows:

1 Board foot or foot board measure (fbm) = 1/12 cubic ft. 

1 Cord foot = 16 cubic ft. 

1 Cord = 128 cubic ft or 8 cord ft.

If you are buying wood green the weight equivalents given by the FAO are: 

Coniferous Wood 39 lbs/cubic foot. 

Deciduous Wood 47 lbs/cubic foot. 

General Wood   45 lbs/cubic foot. 

 

Therefore roughly for green wood 

Coniferous - 60 cubic feet = 1 ton. 

Deciduous - 50 cubic feet = 1 ton. 

Mixed   - 55 cubic feet = 1 ton. 

   

Storing Wood

If the wood you collect or buy has not dried out or 'seasoned' it will need to be stacked out for the sun and the air to evaporate much of the moisture.

The ideal place would be open to fresh air but out of the rain. For some this may not be possible, so choose a hard dry surface that doesn't become waterlogged and drive in stakes for each end of your woodpile. Make sure air can circulate through the stack and that it isn't under trees. You can then stack your cut logs, remembering if possible, to cover them in winter.

 

Woodpile supported by stakes

   

It must be emphasised that these measurements are only rough. The weight of a volume of timber varies with its density and thickness of the logs and how much water it is carrying.

When buying wood we have to take what is available, but it is useful to know what woods have been good for burning on an open fire. As a generalisation the hardwoods are denser contain less moisture and are favoured thus:

 

"Beech wood fires are bright and clear
If the logs are kept a year.
Chestnut only good they say,
If for long 'tis laid away.

Birch and fir logs burn too fast,
Blaze up bright and do not last.
It is by the Irish said
Hawthorn bakes the sweetest bread.
Elm wood burns like churchyard mould,
E'en the very flames are cold.

Poplar gives a bitter smoke,
Fills your eyes and makes you choke.
Apple wood will scent your room,
With an incense like perfume.
Oak and maple, if dry and old,
Keep away the winter's cold.
But ash wood wet or ash wood dry,
A King shall warm his slippers by. "


Anon 

 

Elm wood was plentiful because of the ravages of Dutch Elm disease. There were originally about 23 million trees in the risk area of the South, East and Midlands of England, and about half of these were lost by 1980. Unfortunately, the area of the disease has spread, and another 5 million trees may be lost in the North and East. Elm logs should be left to dry for a full year and then they burn very well in a box stove.

 

Tools

How much preparation you will need to undertake with wood will depend on the form in which you obtain it. If you are lucky enough to have logs delivered in quantity, the right size and thickness for your woodstove, you will save yourself a good deal of work. If not you'll need a few tools.

For cutting and splitting small logs you will need a hand axe and bowsaw. Buy the biggest bowsaw that you can use comfortably. For heavier work you will need a tree axe, a sledge hammer and two steel wedges. You can now buy plastic wedges to keep the split open, or you could make your own hardwood wedges. You will also need a saw horse.

 

  Wood cutting tools

 

If you are cutting a great deal of timber a chain saw is worth considering. Your bow saw will cut through wood up to 6 inches diameter and your hand axe can be used to split these down to thinner pieces if needed. You can cut larger logs up to a foot thick with your bowsaw but it is hard work if you have a lot to do.

The hammer and wedges are essential for splitting thick logs and, with practice, splitting along the line of the grain and avoiding knots, it can be a very satisfying job. However, wedges can be dangerous if they splinter and fly out, so if you want to be really safe, wear a hard hat or crash helmet with an eye shield and use a non metal hammer.

 

  Splitting wood along the grain

   

If you decide that you have enough work to justify 200 - 250 on a chainsaw, then go to your local dealer, explaining your requirements, and listen carefully to his advice. Great care is needed in the handling of this tool and it should only be used with the utmost care. It is a useful idea to get some practice with one, either with a friend who has one, or with the supplier who will gladly demonstrate and show you how to use and maintain it properly. With continual use the chains lose their sharpness quickly so it is useful to have a spare chain. With a file and a guide it is not too difficult to sharpen a chain yourself.

 

Felling Trees

With a chain saw you can undertake the cutting up of trees and the felling of small ones. Large trees or dead trees are a job for experts and should be left to them.  

To cut down a tree, first have a clear idea where it is to land and how much space it will take up when it is down. Make two cuts to form a notch about a third of the way into the tree so that the line of fall is in the centre of the notch. Make a third cut as shown, leaving a small amount in the middle. The tree should then fall, turning first on the centre part as a hinge. With a heavy tree this may break, so watch out for the trunk to kick back over the stump.

 

  Tree felling cuts

Felling trees requires a licence from the Forestry Commission. The exceptions, for trees on your own land, are as follows:

1.         Fruit trees past their prime.

2.         Trees in your garden, providing they do not have a preservation order on them.

3.         Trees with a trunk diameter of less than 3 inches, 6 inches in a coppice.

4.         Trees in a woodland up to a volume of 325 cubic inches in any quarter, in order to improve the growth of other trees.

 

On common land you can collect dead wood.

 

Managing Your Own Woodlot  

If you are fortunate enough to have land, it may be worthwhile having your own woodlot. If the land is level and fertile, you may decide that it is more profitable to give it over to hay and use the income from that to buy in wood. If, however, the terrain is steep and poor, and unsuitable for anything else, then it is definitely a worthwhile proposition.  

There is also the long-term environmental aspect that if one is burning trees, one has the responsibility for replacing them, not only for oneself, but for future generations, and for the well-being of the planet.

   

Tree Planting  

The time to plant trees is in the dormant stage, between October and March, ensuring that the ground is frost-free. Specimen trees should be at least 10' apart, but for coppicing, 6" is adequate.

Dig a hole deep enough to house the roots and base comfortably, then break up the remaining soil in the hole. Insert the young tree and spread the roots out, then return the soil around the roots. Make sure that the soil does not exceed the original 'collar' or soil mark, then firm the earth by treading.

 

  Planting tree                 Wire mesh collar

 

In exposed areas, staking may be necessary, and a good tie is made from old nylon stockings. Wire should never be used as it causes bark damage.  

If there is the likelihood of rabbit damage, protect the saplings with a wire-mesh sleeve, dug into the ground.

 

Tree Nursery  

If you have a sheltered spot with ready access to water, it may be worth having your own small tree nursery for replacement stock. You will obviously have to wait several decades before coppicing some of them, but it is a good plan to have a few seedlings available to fill a vacant spot. Each one is, at least, a future replacement for another tree felled.  

The name of Johny Appleseed, who planted apple pips on his journeys across pioneer America, is still revered.  

Soak the seeds for 24 hours in cold water prior to sowing: this helps to break the dormancy cycle. Sow in a 50/50 peat/sharp sand mixture, in Spring or early Summer.  

Polythene pots are ideal, and if these are stood in a bed of sand in the shade, less frequent watering is necessary.

 

  Germinating seeds

 

Barely cover the seed and ensure that the sowing medium never dries out. Be patient, for you may have to wait several months for some species to germinate.  

Acorns and conkers are particularly popular with children.

Some of the faster growing species will be ready to plant out in November.

 

Harvesting Wood

Old established trees will need pruning excess, dead or diseased branches. Unless the tree is being felled the cuts should be painted with bitumen to prevent disease. Other trees in the woodlot can either be felled completely, and saplings planted in the vacant spot, or felled for coppicing.

   

  Pruning a tree

   

  Felling alternate trees                Coppicing a tree

 

The former involves felling alternate trees in a close-planted copse, to allow the remainder to spread. The latter method involves cutting the tree and leaving a stump which subsequently throws out new shoots. Willow readily responds to this treatment, as well as the fast-growing Eucalyptus. A certain proportion of these off-shoots are then harvested on a regular basis.

 

 

The Environmental Aspect  

Britain is one of the least wooded countries in Europe, with only 8% of the land covered by wood or forest. The Forestry Commission has done much to redress the balance (a 3% increase since the war) but as their main interest is in growing commercial timber, much of the planting is quick-growing conifer. All over the world the numbers of deciduous trees are falling, and Britain is no exception.

The situation in certain parts of the world, notably India, Central Africa, Latin America and the Caribbean, is even more serious. Here, the daily search for firewood by a rapidly increasing population has resulted in the wholesale deforestation of huge tracts of land.

Our tree canopy plays an essential part in the ecological balance. Without trees and hedges, soil erosion occurs, the natural wildlife is dispersed and destroyed, and oil a larger scale the actual climatic conditions may become distorted.  

Both central and local government could give a lead by education and encouragement, in the planting of trees. Some local authorities such as Truro in Cornwall, have set a praiseworthy example, by giving away free seeds of such species as Southern Beech and Monterey Pine to their residents, as well as providing encouragement and information.

Central Government however, with its plans for land nationalisation, has unwittingly drastically reduced the planting of trees on private estates, for the consensus of opinion amongst private landowners is 'tree planting may be good for posterity but why should I do it for the state?'.